GUI.Box within a Collider

Im trying to make a GUI.Box appear once in the Collider, and disappear once out of the collider… but it dosnt seem to work for me.
Then i changed so that when you where in the Collider, it tolf you to Press “K”, and then once pressed K, the box sould disappear… but it dosnt…
Please help, and please be JavaScript, because i dont understand CSharp.

var levelName : String;
var mySize : Rect = Rect(600,400,600,50);
var guiOn : boolean;

function OnTriggerStay(theCollider : Collider) 
 
    {
    	guiOn=true;
     if(Input.GetKeyDown(KeyCode.K)) {
         animation.Play("Gate");
         	guiOn=false;
     }

   }

function OnGUI() {

	if (guiOn){
		     GUI.Box(Rect(400,400,25,25),"[K]");
    	}
   }

enter → Gui on

stay → keypress to deactivate

exit → disable

You will need to play with it a bit